What are two things the tester can do to cause the least negative impact on the overall project schedule, while still ensuring a quality project? code example

Example: how to make sure quality of test execution

Defect reject ratio
Defect rejeaction ratio is the ratio of 
total rejection to total production

Defect leakage ratio
defect leackage is the ratio of total
possibilitay of rejection occurance to
the total production.

How to calculate=
Defect rejection ratio:
    (No. of defects rejected/ total no. of defects raised) X 100
Defect leakage ratio: 
    (No. of defect missed/total defects of software) X 100